1. Field of the Invention
The present invention relates to an MIM (metal-insulator-metal) capacitor used in a semiconductor device.
2. Description of the Background Art
An MIM capacitor has conventionally been used in a semiconductor device. The MIM capacitor includes a metal upper electrode, a metal lower electrode, and a dielectric held therebetween. The lower electrode is arranged closer than the upper electrode to a substrate for holding a semiconductor device.
In an exemplary capacitor disclosed in Japanese Patent Application Laid-Open No. 2001-144266, a ruthenium film forms a lower electrode which protrudes toward an upper electrode. In another exemplary capacitor disclosed in Japanese Patent Application Laid-Open Nos. 8-167702 (1996) and 2000-101047, a lower electrode protruding toward an upper electrode has a fin on the side surface thereof.
In an MIM capacitor, a metal film such as a ruthenium film is used to form a lower electrode, causing difficulty in processing thereof.